Embryo profiling

Embryo quality is the ability of an embryo to perform successfully in terms of conferring a high pregnancy rate and/or resulting in a healthy person. Embryo profiling is the estimation of embryo quality by qualification and/or quantification of various parameters. Estimations of embryo quality guides the choice in embryo selection in in vitro fertilization.

In general, embryo profiling for prediction of pregnancy rates focuses mainly on visual profiles and short-term biomarkers including expression of RNA and proteins, preferably in the surroundings of embryos to avoid any damage to them. On the other hand, embryo profiling for health prediction puts more focus on the genome, and where there is a risk of a genetic disorder it more often involves cell sampling from the embryo for preimplantation genetic diagnosis.

Embryo quality is mainly evaluated by microscopy at certain time points using a morphological scoring system. This has shown to significantly improve pregnancy rates.

Time-lapse microscopy is an expansion of microscopy wherein the morphology of embryos is studies over time. As of 2014, time-lapse microscopy for embryo quality assessment is emerging from the experimental stage to something with enough evidence for broader clinical use. Studies using the EmbryoScope(tm) time-lapse incubator have used several indicators for embryo quality, such as direct cleavage from 1 to 3 cells, as well as the initiation of compaction and start of blastulation. Also, two-pronuclear zygotes (2PN) transitioning through 1PN or 3PN states tend to develop into poorer-quality embryos than those that constantly remain 2PN.

Molecular analysis can be performed by taking one of the cells from an embryo. The analys can vary in extent from a single target biomarker to entire genomes, transcriptomes, proteomes and metabolomes. The results may be used to score embryos by comparing the patterns with ones that have previously been found among embryos in successful versus unsuccessful pregnancies:

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